Technical Field
The present disclosure relates to an antenna device and a corresponding terminal for the antenna device.
Description of Related Art
Terminal devices, such as cellular phones, smart phones, and tablet devices, typically include an antenna apparatus with which to transmit and receive voice and/or data signals. The frequency bandwidth utilization is increasing in these terminal devices. In order to cope with the increase in bandwidth, there exists a method of providing multiple antennas to accommodate a wider frequency spectrum. Additionally, there exists a method of carrying out bandwidth increases utilizing a single antenna.
When a single antenna is used, it is preferable that any increase in bandwidth capacity does not unnecessarily increase the antenna size. Additionally, when carrying out a bandwidth increase using a single antenna, it is preferable not only to ensure favorable performance of each frequency band, but also to optimize Specific Absorption Rate (SAR) of each band to counter effects of SAR that are detrimental to antenna and/or terminal device performance. Previously, conventional cellular phone design was mainly concerned with reducing SAR of a user's head during a telephone call. However, in the case of a smart phone, a design should consider not only reducing SAR of the user's head during telephone calls, but also SAR of the user's body at the time of a data transmission (e.g., Internet transmissions, streaming, etc.), which are often being performed while the smart phone is stored close to the body (e.g., in the pocket of a coat).
U.S. Pat. No. 7,990,321 describes an exemplary multi-band antenna. The antenna as described in this literature is made to support multiple frequency bands (e.g., Global System for Mobile Communications (GSM), Global Positioning System (GPS), Digital Cellular Service (DCS), Personal Communication Service (PCS)) using one antenna feeding portion for passing electromagnetic signals in a plurality of frequency bands. Since a coupled grounding portion is provided in the case of the antenna, it is a premise of the literature to arrange and use the multi-band antenna on a circuit board substrate. For this reason, the countermeasure against SAR is left to the circuit side of a terminal device. This arrangement is problematic because any adjustments needed in the circuit board components involve undesirable increases in manufacturing and materials costs, as well as new printed circuit board (PCB) layout design labor costs.